Modify the accordion object

I am using Adobe Captivate 6.0. After inserting an interaction, the accordion object, I decided to add an additional button after clicking ok. However when I selected the “Gaggets properties” button to go back and add an additional button, the plus sign at the bottom center will not appear to allow me to insert additional buttons. How can I get the plus sign to appear so that I can add an additional button to the accordion?

Thank you,

Karen Williams